Rock drill



F. F. GRAHAM Dec. 28, 1937.

WIAM Il D A ROCK DRILL Filed Dec'. 15,- 1935 INVENTOR. efizfffa/Mm ATTORNEY. f

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Patented Dec. 28, i937 lrt; 1F. G k ton' du Pont, Delaware m u in Cardin, Md.1 asdor to Peycoora e. a corporation oi pplication December i3, i933, @arial N0. 'INAMI drills, and more particularly to that class of drills iapted for use in rock drilling, mining and the Heretofore, drills of the class speciiied included a suitable rod, one end being adapted for attachment to lsuitable power operating mechanism, while, the other end of the rod carrieda drill bit. A passage extended axially through the rod and drill bit and when the drill was in operation, air

or water under pressure could be passed through this axial passage for the purpose of blowing or washing out the rock dust from the hole being drilled. i

1 have found from experience that when a drill of the above described construction rotates in the rock bed, a small round core remains uncut and is driven upwardly into the axial passage, plugging the same. This isv a source of considerable trouble because it necessitates the removal of the drill from the rock bed so that the passage may be cleared. Failure to maintain a clear passage wm greatly reduce the cutting speed ofthe drin because of the presence of the rock dust and chips, which cannot be blown or washed from the drilled hole until air or water is forced through the axial passage.

have devised an extremely simple and enicient means for obviating these diiculties and accordingly this is the main object of my invention.

A more specic object of this invention is the provision of a drill, including a rod. one end of which is adapted to be connected to-an operating means and the other end of which carries a drill bit having integral cutting edges; the drill rod is provided with an axial passage therethrough and the drill bit is also provided with apassage communicating with the axial passage and opening through the drill .bit eccentrically with reference tothe axial passage of the drill rod but being included between the integral cutting edges.

Other objects and advantages oi my invention will `become apparent as the iollowingdescripi tions cut Figure 341s a `perspective view of the lower end ofthe improved drill;`

Figure 4 is a View similar to Figure 3 with poraway to illustrate the invention more clearly.;

will Z-til My invention pertains to improvements in Figure 5 is a view similar to Figure 3 showing a modification of my invention; and

Figure Gis a view similar to Figure d showing a further modification.

In the drawing, il) designates the rock drill as a whole, which is preferably of the Jackhammer type and includes a casing i i for housing the power operating mechanism of the drill. Projecting outwardly beyond'the casing Il is a drill rod i2 having an angular end i3 tted into a chuck l0 It which transmits short, hammer-like strokes and also a rotating motion to the drill rod I2. Since the mechanism which produces this motion is of a well known construction and forms no part of my invention, detail descriptionthereof is not 15 necessary. y

At its lower end, the drill rod i2 carries a bit i5 which includes a cylindrical body portion it having formed integrally therewith a plurality of cutting edges such as I1. Each' cutting edge i'i 20 is formed by the intersection of the substantially triangular shaped side faces I8 which converge toward the axis of the bit i5. In Figures 1 to 4, and 6, these cutting edges do not intersect at a common point but terminate somewhat short `oi' 25 one another, providing a recess vil in order that resharpeningof these bits will be facilitated. If desired; the aplces'of the triangular faces may intersect at a common point P, as shown in Figure 5, and in this manner the bit I5 will then have an 30 axial cutting point and also increased strength at this point. However, it is preferable that the recess 9 be formed, for the purpose whichwill hereinafter appear.

Preferablypthe cutting edges i'l all lie in a com- 35 mon plane and their outer portions i9 extend beyond the limits of the body portion it and the ,-drill rod i2 in order that the hole 2d which is drilled in the rock bed 2i may be somewhat larger than this bodyrportion and drill rod. This con- 4,@ struction permits rock dust and chips to be freely elected from the drilled hole 2d in a manner whichl will be iully described. n

The bit i5 is detachably secured to the lower end of the drill rod l2 by means of the interen- 45 gaging screw threads 22, which are formed at the lower end ofthe drill rod and within the body portion it. These screw threads are of special form and permit the hammerblow of the drill i@ to be transmitted to the cuttingedges il directly 5g through the end face 23 of the rod it which abuts the seat 24' ofthe bit it and notl through the screw threads.V

Drilled'exiallyf through the rod Y i2 is a passage 2E which may extend into the bit .it below the gg seat 24. Between the triangular faces of the adjacent cutting edges I1 I drill a hole or passage 26 which intersects the passage 25 and opens exteriorly between the cutting edges so as to be eccentric with reference to the axis of the drill rod I2. I have found that best results are gained when the holes 26 open exteriorly closely adjacent the axis of the bit I5 so that the compressed air when forced through these holes will impinge directly on the bottom of the hole being drilled to effectively clear the same of rock dust and chips. In other words, it is preferable that the holes 26 be drilled in a manner so that the extended axis of each hole will intersect the plane of the cutting edges I1 within the limits of their outer portions I9. The undercut or recess 9 forms a space between the bottom of the drilled hole and the end of the drill through which space stone chips may be blown by the spreading action of the fiuid emerging from the angular holes 26, from the under side of the drill bit.

Figure 6 shows a further modification of my invention in which the hammer blow of the drill Il) is transmitted to the cutting edges l1 through the abutting shoulders 21 and 28 of the drill rod 29 and bit 30, respectively. That portionv of the bit 30 immediately beneath the end face 3| of the rod 29 is relieved as at 32 and forms with the end face 3| a small chamber 33. A passage 34 is drilled axially through the rod 29 and communicates with the small chamber 33. A single hole 35 of substantially the same diameter as the pissage 34 is drilled between the triangular faces of the bit 30 and enters the chamber 33 to communicate with the passage 34. This hole 35 likewise opens eccentrically with reference to the axis of the drill l0 and it is preferred that this hole also opens exteriorly bf the bit 30 closely adjacent its axis. It will be observed from Figures 1 to 4, inclusive, and Figure 6, that the angularly directed passages 26, 35 cooperate with the undercut of recess 9 to maintain the entire bottom. of the drilled hole clear of stone chips, thereby increasing the drilling speed.

When a drill constructed according' to my invention is placed in operation, some of the compressed air or other fluid which is exhausted from the power operating mechanism of the drill passes through the passage 25 and thence outwardly through the holes 26 to impinge upon the bottom of the drilled hole 20. The rock dust and chips are thus effectively blown out through the spaces 4l) which are formed between the side walls o-f the drilled hole 29 and the body portion l5 of the bit. By drilling the holes 26 or 35 in a manner as described, the bit will effectively drill a hole in the rock without producing any uncut cores of rock such as occurs in constructions wherein the passage 25 opens axially through the bit.

In addition to the illustrated structures, I have considered other modifications to be within the scope of my invention, substantially as dened by the appended claims.

I claim:

1. A drill of the rotary-percussive type including a rodhaving a passage extending therethrough, a bit at one end of said rod, said bit comprising a body portion having a plurality of integral cutting edges at one end thereof terminating beyond the end and radial limits of said body portion, said cutting edges stopping spaces formed between said cutting edges, said bit being provided with an aperture/'for fluid communicating with the passage of said rod and opening exteriorly of the body portion of said bit between the cutting edges thereof and being spaced radially of said central recess.

2. A drill of the rotary-percussive type including a rod having a passage extending therethrough, a bit at one end of said rod, said bit comprising a body portion having a plurality of integral cutting edges at one end thereof terminating beyond the end and radial limits of said body portion, said cutting edges stopping short of such axis to form a central recess in said bit, such recess during operation of said drill constituting an inter-communication for` the spaces formed between said cutting edges, said bit being provided with an aperture for fluid communicating with the passage of said rod and opening exteriorly of the body portion of said bit between the cutting edges thereof and being spaced radially of said central recess, such aperture being angularly directed within the radial limits of said cutting edges.

3. A bit for use with a rotary-percussive drill comprising a body portion having a plurality o1 integral cutting edges at one end thereof terminating beyond the end and radial limits of nating beyond the end and radial limits of said Y body portion, said cutting edges stopping short of such axis to form a central recess in said bit, such recess during operation of said drill bit constituting an inter-communication for the spaces formed between said cutting edges, said bit being provided with an aperture for fluid which opens exteriorly of said body portion between the cutting edges thereof and being spaced radially of -said central recess, such aperture being angularly directed within the radial limits of said cutting edges.

y 5. A 'drill of the rotary-percussive type including a rod havinga fluid passage extending therethrough, a bit at one end of said rod, said bit comprising a body portion having a plurality of integral cutting edges, the inner ends of the cutting edges terminating short of the longitudinal axis of the drill to provide a central recess in the bit, said recess constituting an intercommu-nication for the spaces between the cutting edges and an aperture in the bit connected with the passage of said rod, said aperture terminating between the cutting edges of the bit and in spaced relation to the longitudinal axis of the drill.

6. A bit for use with a rotary-percussive drill comprising a body portion having a. plurality of integral cutting edges, the inner ends of the cutting edge terminating short of the longitudinal axis of the bit to provide a central recess therein, said recess constituting an inter-communication for the spaces between the cutting edges and an aperture for fiuid in said bit terminating between the cutting edges thereof and in edges, means on the bit arranged to engage the spaced relation to the longitudinal axis of said bit.

'7'. A bit for usewith a rotary-percussive drill comprising a bit portion having a plurality of 'integral cutting edges, the inner ends of the cutting edges terminating short of the longitudinal axis oi the bit to provide a central recess therein, said recess constituting an inter-corn-a municat'ion for the spaces between the cutting end portion of a drill rod, and a passage having a discharge aperture in said bit terxinating between the cutting edges thereof and in spaced relation to the longitudinal axis of said bit, and

'arranged to communicate with the end portion 

